Abstract: The present invention is a geolocation system for providing coordinated sensing and precision geolocation of a target emitter. The system may include a Quint Networking Technology (QNT) subsystem which may be configured receiving, detecting and identifying a target emitter signal. The QNT subsystem may be further configured for extracting a carrier phase of the signal. The system may further include a Real Time Kinematic Global Positioning System (RTK GPS) subsystem for determining a position of the geolocation system relative to a position of a second geolocation system. Further, the system may be configured for communicating with the second geolocation system via a QNT communication data link for: determining a QNT time difference via signal carrier phase differencing for calculating a time difference between the geolocation systems and geolocating the target emitter based on both the relative position information of the geolocation systems and the calculated time difference between the geolocation systems.

Abstract: The wireless communication device includes a wireless communication transceiver to generate an oscillator control signal and an activation signal, a positioning-system receiver (e.g. a GPS receiver) to process received positioning signals, and a shared oscillator (e.g. a temperature compensated and voltage controlled crystal oscillator TCVCXO) responsive to the oscillator control signal and to generate a reference frequency signal for the wireless communication transceiver and the positioning-system receiver. The positioning-system receiver may control processing of the received positioning signals based upon the activation signal to reduce a noise contribution (e.g. phase noise) due to frequency control of the shared oscillator based upon the oscillator control signal. The activation signal may indicate that the oscillator control signal is being varied to provide frequency control or adjustment of the shared oscillator.

Abstract: The number of GPS satellites from which radio waves are received and the intensities of radio waves received from the GPS satellites are acquired. In a first state in which radio waves of a first signal intensity are received from four GPS satellites in a first predetermined time, orbit/time information are acquired from the respective GPS satellites. The time information indicates a radio-wave emission GMT clock time at the satellite when the radio waves were emitted from the satellite. In a second state in which radio waves of a second signal intensity lower than the first intensity are received from one or more GPS satellites within a second time longer than the first predetermined time, the time information is acquired from the respective GPS satellites. In the first state, a current time and a current position of the GPS timepiece is calculated based on the time/orbit information. In the second state, a current time is calculated based on the time information.

Abstract: A wireless device including a transceiver that utilizes a power supply is described. The wireless device includes a Global Positioning System (“GPS”) section having a plurality of GPS subsystems and a power controller in signal communication with the power supply and GPS section, wherein the power controller is configured to selectively power each GPS subsystem from the plurality of GPS subsystems.

Abstract: A system and method is provided enabling identification of different PN offsets values for CDMA signals without access to a GPS signal, such as when making measurements within indoor environments. When a timing reference, such as that provided by a GPS signal, is lost, the frame boundary timestamp of the CDMA signal itself is used. The parameters of the strongest available PN offset are used. The timing error is determined and the new timing reference timestamp is estimated. The strongest PN is used as the time reference and tau is corrected for. In further embodiments, a user may be able to provide identifying information allowing the estimated timing reference timestamp to be determined even when a GPS signal was never established for providing an initial timing reference.

Abstract: A method for determining portions of a GPS satellite signal may use non-coherent integration to determine a repeated pattern such as a preamble. Once the repeated pattern is determined, portions of the GPS satellite signal that may be determined with partial correlation sums. Sensitivity to satellite signals may be increased by computing more partial correlation sums on portions of the GPS satellite signal. In one embodiment, time of day information may be determined from the GPS satellite signal with partial correlation sums.

Abstract: A method of acquisition of a received signal received from a global navigation satellite system, includes: obtaining a snapshot of the received signal; correlating the snapshot with a locally-generated signal, wherein the correlating includes: trying a phase delay value indicative of a hypothesized phase delay of the locally-generated signal with respect to the snapshot; and obtaining a partition of the snapshot and the locally-generated signal into corresponding pluralities of blocks, and calculating partial correlation integrals for each block of the plurality of blocks. The corresponding pluralities of blocks each include a first block having a time duration related to the phase delay value.

Abstract: A positioning method includes (a) executing a cumulative addition for either one of the polarities on each of an I Q components of0 a received positioning signal, which is spread-modulated with a spread code reversed in polarity by navigation data, (b) calculating sum of squares of the result of the cumulative addition, (c) calculating correlation between the sum of squares and a replica code of the spread code, and (d) executing a positioning calculation of the present location based on the result of the correlation calculation.

Abstract: An electronic timepiece having a function for receiving satellite signals transmitted from positioning information satellites, including a satellite signal reception unit that receives the satellite signals, a satellite capturing unit that executes a process of capturing the positioning information satellites within a capture time based on the satellite signals received by the satellite signal reception unit, a time adjustment information generating unit that acquires satellite information from the satellite signal sent from the positioning information satellite captured by the satellite capturing unit, and generates time adjustment information based on the satellite information, a time information adjustment unit that adjusts internal time information based on the time adjustment information, a time information display unit that displays the internal time information, and a time limit setting unit that variably sets a time limit for the time adjustment information generating unit to generate the time adjustm

Abstract: Methods and apparatus are provided for operatively enabling at least a first receiver path to receive a first signal associated with a first satellite positioning system (SPS), operatively enabling at least a second receiver path to receive a signal associated with at least one other SPS, and subsequently operatively enabling at least the second receiver path to receive a second signal associated with the first SPS.

Abstract: A method of receiving a global navigation satellite system (GNSS) signal in a GNSS reception apparatus is provided. The method includes the steps of: measuring channel quality for each frequency band; selecting a plurality of reception channels by using the measured channel quality; reconfiguring an operating parameter of the reception apparatus in accordance with the reception channel; and receiving a signal by using the reconfigured operating parameter.

Abstract: A method and apparatus for estimating oscillator signal variation due to temperature and for providing an estimated frequency to a GPS receiver in order to assist the GPS receiver to acquire the signals quickly is disclosed. A temperature sensor is closely thermally coupled with the crystal oscillator in the GPS receiver and during GPS tracking mode, when the error in the oscillator signal is known with precision, outer bounds of TCXO frequency at given temperatures are maintained, which may correspond to rising and falling temperature conditions. During acquisition mode, an estimated frequency value is provided to the GPS receiver based on a determined average of these bounds. Optionally, an uncertainty factor associated with the frequency estimated may also be provided. The two bounds take into account the hysteresis effects of the oscillator signal drift due to temperature so that a more accurate initial frequency estimate can be provided to the GPS receiver, thus reducing its average time to first fix.

Abstract: The subject innovation relates to a chip card to be inserted in terminals. An exemplary embodiment of the chip card includes a clock unit to provide a time reference and an internal power source to at least run the clock unit in case of absence of an external power source. The exemplary chip card also includes a signal receiver to receive a satellite navigation signal comprising a satellite time signal, the signal receiver being connected to the clock unit in order to synchronize the clock unit with the satellite time signal to enable the clock unit to provide the time reference as a trusted absolute time reference independently from a position of the chip card.

Abstract: Disclosed is a method for acquiring a signal of a satellite by a receiver, including pre-storing weighting factors of satellites, which include possibility indexes of satellite signal acquisition with respect to positions and times of the receiver, receiving a request for acquisition of the satellite and initializing operational status information and search history information of the satellites, searching for the satellites in sequence according to the weighting factors, resetting the operational status information and search history information of the satellites based on whether signals of the satellites are detected, updating the weighting factor of a satellite having a signal that has been detected, and selecting the satellite having the signal that has been detected in consideration of the updated weighting factor, and acquiring the signal from the selected satellite.

Abstract: A global positioning system (GPS) system includes a clock module for providing multiple counter values at multiple time points. The GPS system also includes a system module coupled to the clock module. The system module is capable of obtaining a time value for each time point according to a set of signals from a signal source. The system module is further capable of calculating a set of parameters based on the counter values and the time value for each time point, and determining an estimated time value based on the parameters and a present counter value from the clock module.

Abstract: A low complexity acquisition method and a receiver implemented such a method are disclosed. In the present invention, a cyclical shifted-and-combined (CSC) code is generated by intercepting sub-codes from a full code and combining the sub-codes with an equal gain. The CSC code is correlated with a received signal to find a candidate peak. The other candidate peak(s) can be deduced accordingly. Thus, hypotheses can be significantly reduced. A true peak can be easily and rapidly found by verifying the candidate peaks.

Abstract: Disclosed is a satellite radiowave receiver which obtains a satellite signal transmitted from a positioning satellite including a receiving unit which receives a radiowave in a frequency range which is set in advance, the frequency range including a frequency transmitted by the positioning satellite transmit, a capture unit which detects the satellite signal from a received signal based on the radiowave received by the receiving unit and a calculation unit which calculates a mean frequency of a plurality of the satellite signals which are detected, based on receiving frequencies of the plurality of the satellite signal detected by the capture unit, and the capture unit detects the satellite signal according to the mean frequency.

Abstract: A handheld electronic device, such as a GPS-enabled wireless communications device with an embedded camera, a GPS-enabled camera-phone or a GPS-enabled digital camera, determines whether ephemeris data needs to be obtained for geotagging digital photos taken with the device. By monitoring user activity with respect to the camera, such as activation of the camera, the device can begin pre-acquisition of a GPS position fix by obtaining needed ephemeris data before the photograph is actually taken. This GPS pre-acquisition improves the likelihood that a position fix (GPS lock) is achieved by the time the photo is taken (to enable immediate geotagging). Alternatively, the photo can be geotagged retroactively by appending the current location to the metadata tag associated with the digital photo. An optional acquisition status indicator can be displayed on a user interface of the device to indicate that a position fix is being obtained.

Abstract: A signal processing system for processing satellite positioning signals is described. The system comprises at least one processor and a signal processor operating under a number of operational modes. The signal processor includes at least one of a signal processing subsystem, a fast Fourier transform (FFT) subsystem, and a memory subsystem that are each dynamically and independently configurable in response to the operational modes. Further, the system includes a controller that couples to control transfer of data among the signal processing subsystem and the FFT subsystem via the memory subsystem. Configurability of the memory subsystem includes configuring the memory subsystem into regions according to the operational modes where each region is accessible in one of a number of manners according to the operational modes.

Abstract: The present invention is related to location positioning systems, and more particularly, to a method and apparatus of synchronizing to data frames in a positioning system signal. According to one aspect, the invention speeds up the frame synchronization process by computing a frame synchronization metric for each satellite and then combining together the metrics for all tracked satellites together, after compensating for respective signal transit times. Then the invention makes a frame sync decision on the combined satellite metric. In embodiments, an optimal combining algorithm is used based on CNO of each satellite. According to further aspects, the invention further speeds up the frame synchronization process by predicting many bits in the subframe so that more bits are known in addition to the 8-bit preamble. For example, the invention recognizes that many bits in a subframe rarely change or don't change very often. Moreover, the invention uses old ephemeris used to predict new ephemeris parameters.

Abstract: Systems and methods are disclosed to use adaptive continuous tracking (ACT) to reduce the power consumption of GNSS receivers. In GNSS receivers, a longer observation time of the satellites translates into better positioning accuracy but also consumes more power. ACT allows satellite observation time to be tuned to the desired positioning performance by dynamically adjusting the on time period of the receivers while maintaining a minimum performance metric. The performance metric may be formed from a combination of the estimated position error, the horizontal dilution of precision (HDOP), the data collection state, and the receiver operating environment as characterized by the carrier to noise ratio (CN0).

Abstract: Method and apparatuses involving satellite position signals are disclosed. Based on data indicating a usage environment, parameters, for example acquisition parameters or calculation parameters, are adapted.

Abstract: A satellite signal reception device according to an aspect of the invention comprises a reception operation unit that executes a reception operation process to receive a satellite signal transmitted from a positioning information satellite and generates positioning information from the satellite signal. The satellite signal has precise and coarse information orbit periods containing precise and coarse orbit information respectively for the positioning information satellite. The reception operation unit executes the reception operation process in the precise orbit information period, uses the coarse orbit information period as a suspended reception period, and pauses at least a part of the reception operation process in the suspended reception period.

Abstract: A satellite signal tracking method performed by a receiver that receives a satellite signal from a positioning satellite, the satellite signal tracking method including: computing a first Doppler frequency using a received signal obtained by receiving the satellite signal, computing a second Doppler frequency using the first Doppler frequency and a signal from the sensor unit including at least an acceleration sensor, and acquiring the satellite signal using the second Doppler frequency.

Abstract: A method and a mobile device configured to obtain position information from a position broadcast system, the position broadcast system comprising a plurality of transmitters that each broadcast a respective signal containing position information for the respective transmitter. The method comprising: measuring signal strengths of signals from a plurality of the transmitters of the position broadcast system; and determining that the mobile device is out of range of the position broadcast system if the measured signals strengths satisfy at least one out of range criterion.

Abstract: A Global Navigation Satellite System (GNSS) device, such as the Global Positioning System (GPS) device, uses satellite orbital position information from almanac and/or ephemeris data to change a search parameter, such as reducing the number of analyzed frequency bins or setting signal strength threshold, so that satellite signal acquisition times are reduced. An exemplary embodiment estimates an orbital position for at least one GNSS satellite based upon at least one of almanac data and ephemeris data, detects a signal emitted from the at least one GNSS satellite, and based upon the estimated orbital position information for the at least one GNSS satellite that is determined from the almanac data and the ephemeris data, adjusts at least one parameter used in the analysis of the detected signal.

Abstract: A set of device parameters consisting of clock bias and position of a mobile device is determined without previous knowledge of the week number (WN) in that solutions of a set of equations derived from a least squares type weight function involving pseudoranges related to the device parameters via basic equations are attempted with a time of week (TOW) extracted from satellite signals and various week number candidates. A solution algorithm which iteratively solves the set of equations is used, each iteration step involving a linearization of the latter and resulting in corrections of the device parameters. After elimination of week numbers where the solution algorithm does not yield a solution a valid week number is selected from the remaining week numbers in that a deviation value is determined which reflects differential terms, i.e., differences between pseudorange values as measured and as derived from the set of device parameters according to the solution, e.g., by evaluation of the weight function.

Abstract: A fast position tracking method and apparatus, the fast position tracking method including the operations of receiving a satellite signal from a plurality of satellites; demodulating satellite data received from a predetermined satellite from among the plurality of satellites by using a pseudo random noise code and a carrier which correspond to the satellite signal; estimating information about satellite data which is at a current time and which is from among the demodulated satellite data according to a real-time clock (RTC) counter; and determining a position.

Abstract: A GNSS enabled communication device receives GNSS signals from GNSS satellites. The resulting GNSS baseband signals may be concurrently correlated with GNSS acquisition codes. Inter-delay products for the received GNSS signals may be generated utilizing the correlation IQ samples. The inter-delay products are utilized to calculate either an open loop or a close-loop estimate for inter-delay phase coherence of the received GNSS signals. A test statistic, generated from the inter-delay products, may be compared with a preset or dynamically determined threshold value in order to detect or declare signal degradation effects in the received GNSS signals. The early and late delays for the inter-delay phase coherence may be generalized to two or more delays. In this regard, the correlation IQ samples may be utilized to generate a correlation matrix. Variations derived from the correlation matrix may be utilized to declare or detect signal degradation effects in the received GNSS signals.

Abstract: Embodiments of the invention provide a method of reacquiring satellite signals quickly. A pseudorange of at least one satellite is estimated. A user's position is also estimated. Then a signal from at one or more satellites may be received. By detecting when the user is stationary, the Doppler frequency estimation can be corrected or the SNR can be boosted more both of which lead to improved performance. The embodiments allow a GNSS receiver to process signals in when the signal level would otherwise be too low—for example indoors. The embodiments can improve performance when one or more satellites are temporarily blocked but one or more satellites are still being tracked.

Abstract: A GNSS enabled handset receives signals from different resources comprising GNSS satellites and/or from a wireless network. The GNSS enabled handset acquires location information comprising various positioning resource data comprising GPS data and/or WiFi data from the received signals. The GNSS enabled handset calculates a plurality of possible position fixes based on the acquired location information using various positioning approaches. A current position fix associated with the GNSS enabled handset is determined based on the plurality of calculated possible position fixes via running a location-based service (“LBS”) client on the GNSS enabled handset. The LBS client determines the plurality of possible position fixes using various positioning approaches in a particular or determined order. Confidence levels for each of the calculated plurality of possible positions are determined and used to refine the current position fix.

Abstract: A method and apparatus for processing satellite positioning system (SPS) signals which are weak in level. In one embodiment, a SPS receiver receives at least two signal samples representing, at least in part, common information, wherein the two signal samples are associated with one or more satellite messages. By combining the two signal samples, navigation information (e.g., time, position, velocity, etc.) may be determined based on the combination of the two signal samples. According to another embodiment, the two signal samples are differentially demodulated and summed together to form the combination.

Abstract: A method of tracking a position of a transmitting apparatus in a sensor network is provided. The transmitting apparatus may receive Global Positioning System (GPS) information from each of satellites, may extract satellite time information and satellite identification information from the GPS information, may generate a transmission frame together with receiving time information and apparatus identification information, and may transmit the transmission frame to a receiving apparatus.

Abstract: The subject matter disclosed herein relates to a system and method for acquiring signal received from space vehicles (SVs) in a satellite navigation system. In one example, although claimed subject matter is not so limited, information processed in acquiring a signal from a first SV may be used in acquiring a signal from a second SV.

Abstract: A system comprises a Global Navigation Satellite System (GNSS) receiver configured to acquire and track a unique radio frequency (RF) signal for each of a plurality of channels, wherein the GNSS receiver is configured to provide one or more system state measurements based on the unique RF signals; processing functionality configured to calculate a respective code delay error for each of the plurality of channels based on the respective unique RF signal; and micro jump detection functionality configured to calculate an average code delay error across all of the plurality of channels based on the plurality of calculated code delay errors, wherein the micro jump detection functionality is further configured to compare the calculated average code delay error to an error threshold to detect a micro jump event when the calculated average code delay error exceeds the error threshold.

Abstract: A positioning system receiver that mitigates cross correlation of received signals from positioning system satellite vehicles by generating the strong satellite vehicle signal and subtracting it from the received signal before correlation while eliminating the need for cross correlation signature without changing the C/A code.

Abstract: Methods and systems are provided for accessing GPS signals in faded environments. Means are provided for predicting the nonlinear phase induced by the receiver's own clock, when there is at least one GPS satellite link strong enough to calculate a phase profile. In an embodiment, GPS signals are accessed in faded environments by increasing the sensitivity of a GPS receiver by increasing the processing gain of received GPS signals through increased integration time. Matching a near-baseband signal requires removing a nonlinear part of the phase which may arise from several sources, including: the phase drift of the GPS satellite's atomic clock, the phase drift due to the motion of the GPS receiver, the phase drift due to the motion of the GPS satellite, and the phase drift due to the GPS receiver's clock.

Abstract: The present invention relates to a method and an arrangement in a mobile telecommunication network for detection of a UE transmitted signal. The arrangement comprises means for detecting the signal during the time ttot, wherein said means comprises a correlator adapted for combined coherent and non-coherent correlation, wherein the length of the coherent correlation interval is L signal samples, the number of coherent correlation intervals is M and the coherent correlation results in a coherent correlation result for each of the coherent detection intervals M, and means for adding the coherent correlation results non-coherently. Further, the arrangement comprises means for selecting one of the length L of coherent detection interval and the total detection interval ttot based on at least one of the parameters cell size, UE speed and acceleration, number of participating Location Measurements Units and a desired total false alarm rate.

Abstract: The subject matter disclosed herein relates to a system and method for processing navigation signals received from multiple global navigation satellite systems (GNSS'). In a particular implementation, signals received from multiple GNSS' may be processed in a single receiver channel.

Abstract: The first reception operation is started in response to an acquisition request. Power supply to a RF unit and a demodulator is stopped after synchronization with the GPS signal is established. Based on information acquired from a sub-frame in the GPS signal, a time point to start the second reception operation is determined. Elapsed time is counted using a counter clock synchronized with transmission timing of the navigation message, while a reception frequency of the satellite, a PRN code unique to the satellite, and a frequency and a phase of the PRN code are retained. When the elapsed time arrives at the time point, the power supply to the RF unit and the demodulator is restarted.

Abstract: A method for calculating current position coordinate and a method for calculating a pseudo range are applied to a global positioning system (GPS) receiver. A position coordinate of the GPS receiver at the positioning time point is calculated through an average pseudo range between the GPS receiver and each satellite at a positioning time point. With regard to calculating the average pseudo range between the GPS receiver and each satellite, for each satellite, original pseudo ranges are obtained through calculating a pseudo range between the satellite and the GPS receiver at each millisecond (ms) in a time range including the positioning time point, and then the average pseudo range between the satellite and the GPS receiver at the positioning time point is obtained through calculating an average value of the obtained original pseudo ranges between the GPS receiver and the satellite.

Abstract: A method of acquiring a signal includes generating a first set of acquired signal power values comprising an acquired signal power value for each of a plurality of Doppler bins over a first predetection integration time (PIT) interval, and generating a second set of acquired signal power values comprising an acquired signal power value for each of the plurality of Doppler bins over a second subsequent PIT interval. The first and the second sets are used to generate at least three additional sets of acquired signal power values. A new set is generated by selecting the maximum of the summations for each Doppler bin from the three additional sets, and a Doppler shift is identified from the Doppler bin having the maximum summation value. The output may be used to initialize a first and a second extended Kalman filters for tracking a carrier signal and a code signal, respectively.

Abstract: A tracking system includes a global positioning system (GPS) module and a modem for mobile communications both attached to a pet (or other trackee), and a virtual fence (which includes a base station sending a signal to a certain range and a receiver attached to the pet (or other trackee) and receiving the signal sent by a base station when the receiver is within the range of the base station). A portable virtual fence system includes a signal-sending base station, and a signal-receiver worn by a to-be-fenced pet or other trackee. Advantageously, the base station is portable. The size of the virtual fence can be expanded to fit any shaped geometry using signal repeater or transceiver devices. In addition, more than one pet can be tracked using a single virtual fence and base station.

Abstract: An apparatus and method for cross-correlation spur mitigation comprising choosing from a plurality of peak measurements, a first peak measurement with a first carrier-to-noise density estimate and a first Doppler offset measurement, and a second peak measurement with a second carrier-to-noise density estimate and a second Doppler offset measurement to form a pair; calculating a carrier-to-noise density difference based on the first carrier-to-noise density estimate and the second carrier-to-noise density estimate; calculating a Doppler difference based on the first Doppler offset measurement and the second Doppler offset measurement; comparing the carrier-to-noise density difference to a carrier-to-noise density threshold; and comparing the Doppler difference to at least one Doppler threshold.

Abstract: A satellite signal reception device having a reception unit that captures a positioning information satellite and receives a satellite signal transmitted from the captured positioning information satellite; a data acquisition unit that can acquire time information and positioning information based on the satellite signal received by the reception unit; and a reception mode control unit that controls the reception mode of the reception unit to at least one of a time information reception mode and positioning information reception mode. The reception unit includes a correlation unit that determines a correlation between a code used for capturing the satellite signal and the received satellite signal. The data acquisition unit includes an operating unit that decodes the received data. The reception mode control unit includes a clock control unit that separately controls the operating clock of the correlation unit and the process clock of the operating unit according to the reception mode.

Abstract: Systems and methods are disclosed herein to dynamically vary supply voltages and clock frequencies, also known as dynamic voltage scaling (DVS), in GPS receivers to minimize receiver power consumption while meeting performance requirements. For the baseband circuitry performing satellite acquisition and tracking, supply voltages and clock frequencies to the baseband circuitry are dynamically adjusted as a function of signal processing requirements and operating conditions for reducing baseband power consumption. Similarly, the supply voltage and clock frequency to the processor running navigation software and event processing are dynamically adjusted as a function of navigation performance requirements and event occurrences to reduce processor power consumption.

Abstract: A satellite signal tracking method includes : detecting a situation of movement; calculating an error of the detection; and setting a loop bandwidth of a tracking filter, which is used to track a satellite signal received from a positioning satellite and of which the loop bandwidth can be changed, using the detection result and the calculated error.

Abstract: An adaptive time-division multiplexing receiver and method for a GNSS system using pilot and data channels for each satellite are disclosed. According to the present invention, multiplexing hypotheses of correlation are properly distributed to pilot and data channels. The pilot and data channels of one satellite can be dealt with as two satellites. Alternatively, correlation is mainly executed to the pilot channel. After the pilot channel is acquired, information such as code phase and Doppler frequency of the satellite are known. Therefore, the data can be demodulated based on the known information.

Abstract: A global navigation satellite system (GNSS) enabled mobile device may be operable to monitor and determine counts at which autoblank signals are asserted over time intervals corresponding to consecutive time windows during the RF interference mitigation process using autoblanking. The GNSS enabled mobile device may be operable to disable the generation of a blank signal when the count may be greater than a particular count threshold at the end of the time window. The GNSS enabled mobile device may be operable to enable the generation of a blank signal when the count may be less than or equal to a particular count threshold at the end of the time window. The blank signals may be used to blank the processing of the received GNSS signals.

Abstract: A slice set for a specific period of time is acquired from a storage area of a memory which is a ring buffer while changing the read position, and the signal strength total value of each slice set is calculated. The signal strengths of the slices included in the maximum strength slice set and the signal strengths of the slices preceding or subsequent to the maximum strength slice set are calculated, and the final signal read position is determined based on a read offset of the maximum strength slice. A GPS satellite signal is acquired and tracked based on the slice read from the determined signal read position, and a specific positioning process is performed.